Why are leveling agents used in paint formulations?

The main function of coatings is decoration and protection. If there are flow and leveling defects, it not only affects the appearance but also damages the protective function. If shrinkage occurs, it will cause insufficient thickness of the paint film, and the formation of pinholes will lead to discontinuity of the paint film, which will reduce the protective effect of the paint film. This requires adding leveling agents to the coating.

During the construction and film-forming process of coatings, physical and chemical changes may occur, which, along with the properties of the coating itself, will significantly affect the flow and leveling of the coating., If there are external pollutants, it may also cause leveling defects such as shrinkage holes and fish eyes.

After coating application, new interfaces will appear, usually the liquid/solid interface between the coating and the substrate, and the liquid/gas interface between the coating and air. If the interfacial tension between the liquid/solid interface of the coating and the substrate is higher than the critical surface tension of the substrate, the coating cannot spread on the substrate, naturally resulting in leveling defects such as fish eyes and shrinkage cavities.

The properties of the coating itself, such as construction viscosity, drying time, etc., can also have a significant impact on the final leveling of the paint film. Excessive construction viscosity and short drying time often result in poorly leveled surfaces.

Therefore, it is necessary to add leveling agents to help the coating achieve good leveling by adjusting the changes and properties of the coating during construction and film formation.